99 Chevy Tahoe 5.7l. No start.

[Carla Jean simmons]

who can help me with a no start problem on my 99 Chevy Tahoe 5.7l 4 wheel drive? or where to go for help.

 

On my 99 Chevy Tahoe 5.7l vortex.. No codes, no security light. Truck just died like it ran out of gas. Now I have a no 

Start issue for a month. On the ICM mounted beside the coil with a 4 pin connector, it has a

Pink wire tests 12volts, and a white wire tests 1 to 4 volts also the LED light flashes, and a 

Black with white stripe wire which is the ground it tests good, the fourth wire is white with a black stripe which 

Is the switching signal and I can not get a signal out of  the circuit. 

I have had the ICM tested and they say its good. I have ohm it myself and all prongs read the same any way I put my leads

But the switching signal doesnt . it reads

With red on ground and black on the switching signal it reads 2.671 mega ohms

With black on ground and red on switching signal it reads absolutely nothing.

Why is the switching signal not reading?

Does that mean my ICM is bad? Please help.. Thank you

Edited October 2, 2019 by txab

[Jsdirt]

Just verify your 5v reference is still good - check it at the MAF sensor. If you have 12v on it there, you might have a reference circuit shorted to battery voltage.

[riverbanks]

Do you have instrument lights when key on?(dash)

[Carla Jean simmons]

 yes i do. would u like to know what its doing and not doing and what i have replaced and all i have tested

[CamGTP]

Yeah, that would be helpful.

 

Like when you turn the key to start it does it just click? Does the starter engage and rotate the engine?

[riverbanks]

Yes,more info the better,many people here to assist

[Carla Jean simmons]

yes my Tahoe cranks but does not start. it going on 3 weeks now. i got in the Tahoe and started it. i let it idle to warm up and i backed out tge driveway and when i put it in drive pushed on gas peddle and it died. hasnt started since. no warning no nothing. here is a list of everything i have done and replaced and tested.... give me a few min.. BTW... thanks 

[Carla Jean simmons]

Here is a list of all the things I have done and tested:

Bought new crank sensor. Tested 12 v good ground. Checked signal to PCM. All is okay.
To make sure I'm not tripping, I pierced all three wires at PCM, all had same reading and are good.
Then replaced ICM 4 wire, all checked out good with voltage. 
Checked signal and ground at com all checked good.
Checked coil have power to it, the signal wire white and black is giving signal. But no fire out of coil. Absolutely none. 
On the ICM, we do have trigger signal from PCM, and do no have signal coming from the ICM.
Changed cam sensor, okay checked good. 
Changed Distributor cap, and rotor button they check good.
Changed all plug wires, pulled all plugs checked them. And they check good.
Changed ignition cylinder, and column. 
Just for shits and giggles I took distributor out and put #1 TDC. 
On the coil the link wire is positive, white tachometer, and black and white ignition signal, I took another plug and put on the coil link wire on connector which is 12v without anything connected to. With key on 12v going on and 12v coming out of white wire wire and white and black wire. 
I had a code of 1351, said ground #1 cylinder. How can the ICM send the ignition signal to the coil when the coil is putting out 12v? 
Signal goes to icm from pcm but nothing comes out of icm

T

[Carla Jean simmons]

 

I have correct readings going into the ICM but nothing coming out of the ICM. Why is that?

[riverbanks]

1351 is most likely,bad Icm, who's did you purchase?

[Carla Jean simmons]

The standard replacement from orileys. I have had it tested and its good. Here is the kicker i boyght 3 of them and all three are doing the same. 

[Carla Jean simmons]

I have a 99tahoe with 5.7 vortec
Truck just shut down leaving driveway. I have change crankshaft sensor, can sensor, icm plug wires. I get no signal to the coil from icm. I have ohm wires from pcm I've check voltage to all sensors there good. I've check all the signals from ckp, to camsenor, to icm to knock sensor. I've owned wires from senors to pcm. I've check for my ground. I can't get the icm to send signal to coil. I get the signal from pcm to the icm but that's as far it will go. Don't tell me the icm is bad cause I've have tried 5 different icm, bought new one and the last 3 of the I had tested at store before I left. What the heck. By the way I've got good fuel pressure check all the fuses. All the sensors that are responsible in starting the truck check out right. From ground to signal. I can't get the icm signal to coil
No security light is on, no codes. One thing I'd like to know on my coil I have a plug in that had 3 termials one is pink wire which is my 12 volts, the other one in middle is the white wire for the tech, the 3rd circuit is the Whittemore and black stripe wire that the icm sends its signal to coil to make it fire. OK on all three circuit I have 120 volts coming in on pink wire I have 12 volts coming out on the tech wire, a different 12 volts coming out of the white/black strip down it which is my signal wire from icm. How can you push 12 volts to a 5 volt circuit. When I turn key on the coil would be sending 12 volts to the icm 5 volt circuit on signal wire. How is that. Is there someone out there that think so they can tell me a Indian trick of why it won't produce a signal to coil to fire. I've asked and asked who can be smarter than anyone else out of 1000 so of people 
Please show me and make me feel stupid. I've check voltage ohm wires. I've been. Working on this for 3 weeks still haven't got anywhere 
I know someone has had the same problem out there as I do. Help me

[Doug_Scott]

The obvious way you "push 12v" is to check the voltage on the circuit by pulling the connector off and checking the voltage on the now open circuit.  If you take any circuit, pull the ground connection off the circuit then test the voltage on that very same ground wire, you will get a 12v signal.  Doesn't matter how far away that connection is from the ground location.

 

You need to stop the "just because" diagnostic logic.  Go back to the beginning, calm down, and slow down on the testing.  Don't skip any tests, and never make more than one change at a time.   You very likely have passed by the problem already.  Don't be afraid to retest something from the other side.  I don't know if manufacturers still have troubleshooting sections in their factory service manuals anymore, but, Chrysler did back in the 70s-80s, saved my ass a couple of times.  

 

One more thing, if you test like you write, you are not careful in what you are doing.  You are very likely right in that someone has come across this before, but it was likely only once, and long forgotten. 

[txab]

Have you tried Youtube? Lots of good videos on all kinds of testing

[Carla Jean simmons]

the icm has power going to it and signal to it, but nothing coming out to the coil. Why would that be

[Jsdirt]

Check out Paul Danner on Youtube and on his website. The Youtube channel name is ScannerDanner, and his channel is Scannerdanner.com - his Premium Channel is well worth the $11 a month. I can just about guarantee you'll find the problem yourself after watching the Premium Channel.

 

Sounds like you have an input problem, wiring problem, or output problem with the PCM. Powers and GROUNDS need to be checked at the PCM. Ohm checks on wiring are no good - you need to disconnect the wiring you wish to test at BOTH ends, and power a halogen bulb, or old school sealed beam headlamp through the wiring - if the wiring can handle that (especially with both high and low on at the same time), and lights the light good and bright, you know 100% that the wiring is good. From there, you can check everything else. A bad-out-of-the-box crank sensor is also a very likely possibly. 

 

I didn't read the whole thread, so forgive me if I'm repeating something ... but don't buy parts at any chain parts stores except for NAPA  . I've found their stuff to be quite a bit more reliable than Auto Zone, Checker/Schucks/Kragan auto parts (or whatever they are called these days), Pep Boys, O'Reilly's, etc.. If you can't find a NAPA, buy Denso, NGK,  Bosch, or OE parts off Rock Auto, or wherever you can find them (preferably not at any dealership).

Edited September 2, 2019 by Jsdirt